Psychological and physiological changes during basic, underwater, demolition/SEAL training

This longitudinal study examines the growth of psychological characteristics and adaptation of physiological markers of stress during a six-month assessment and selection course for U.S. Navy SEALs. Resilience, hardiness, and grit instruments were used to evaluate the psychological characteristics. Blood samples were taken to determine physiological markers related to stress adaptation; specifically, evaluating DHEA, DHEA-to-cortisol ratio, BDNF, NPY, and cortisol. Data was collected at four timepoints throughout the assessment and selection course from 353 students over three classes. Results indicated that resilience and hardiness grow after an initial decline, DHEA and DHEA-to-cortisol increased suggesting physiological adaptation. However, psychological and physiological markers do not exhibit the same growth patterns for participants in the course. This study enhances the understanding of psychological growth and physiological adaptation in a high-stress environment over an extended duration.